The busway, the first section of which opened in 2007 after two years of construction, is used by a number of Metrobus lines which operate within this ‘closed’ system carrying 800,000 people daily. The Turkish authorities have since assisted with the development of a similar system in Lahore, Pakistan, which opened in 2013. The name Metrobüs was coined by the transit agency to suggest that this system is a hybrid between a metro train (Turkish: metro) and a bus (Turkish: otobüs).

The busway opened on September 17, 2007.[4] It was then extended in an easterly direction from Topkapı to Zincirlikuyu, and then from Zincirlikuyu to Söğütlüçeşme, which is on the Anatolian side of Istanbul. In 2012, it was extended from Avcılar to a western residential suburb, Beylikdüzü.[5]

The busway is approximately 50 km (31 mi) in length and has 45 stations,[6] with one lane each direction following Istanbul's main highway .

The system mainly follows the city's ringroad, with a fully separated right-of-way between Avcılar and Zincirlikuyu and between the eastern end of the Bosphorus Bridge and Söğütlüçeşme. There are no intersections with a dedicated bus lane in each direction with few passing lanes.[3] Buses drive on the left-hand side of the bus lane, so that their doors, designed for conventional operation with door to the right-hand side of the vehicle, open onto the bidirectional central platforms. Most services operate only with the ‘closed’ BRT system however.

The following table shows the interval between buses (headway) for each of three sections of the line for vehicles traveling in an easterly direction; intervals for buses in the other direction are similar.[7]

It has been suggested that Phileas buses, which are now rarely used, were underpowered and not strong enough to carry heavy passenger loads and climb steep hills typical in Istanbul, though the hillclimbing aspect of this perception does not appear to have much evidential basis.[8] IETT's stated loading capacity (no. of people) for the buses was considerably higher than that of the manufacturer[citation needed] The Phileas buses were designed with the capacity to use an electronic guided bus system.[9] The one-way Metrobus lanes become blocked whenever a bus breaks down causing delays for the buses in that direction.[10]

The makers of the Phileas buses’ APTS’ were taken to court in 2010 by IETT over the failures.[11] An official investigation was launched by the government with the company.[citation needed]